e82cd9b62c
This PR refines how the `apply` tactic (and related tactics like `rewrite`) name and tag the remaining subgoals. Assigned metavariables are now filtered out *before* computing subgoal tags. As a consequence, when only one unassigned subgoal remains, it inherits the tag of the input goal instead of being given a fresh suffixed tag. User-visible effect: proof states that previously displayed tags like `case h`, `case a`, or `case upper.h` for a single remaining goal now display the input goal's tag directly (e.g. no tag at all, or `case upper`). This removes noise from `funext`, `rfl`-style, and `induction`-alternative goals when the applied lemma introduces only one non-assigned metavariable. Multi-goal applications are unaffected — their subgoals continue to receive distinguishing suffixes. This may affect users whose proofs rely on the previous tag names (for example, `case h => ...` after `funext`). Such scripts need to be updated to use the input goal's tag instead. --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
75 lines
2 KiB
Text
75 lines
2 KiB
Text
universe u
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axiom elimEx (motive : Nat → Nat → Sort u) (x y : Nat)
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(diag : (a : Nat) → motive a a)
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(upper : (delta a : Nat) → motive a (a + delta.succ))
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(lower : (delta a : Nat) → motive (a + delta.succ) a)
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: motive y x
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/--
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error: Invalid alternative name `lower2`: Expected `lower`
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---
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error: unsolved goals
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case upper
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q d : Nat
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⊢ q + d.succ > q
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---
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error: Alternative `lower` has not been provided
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-/
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#guard_msgs in
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theorem invalidAlt (p: Nat) : p ≤ q ∨ p > q := by
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cases p, q using elimEx with
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| lower2 /- error -/ d => apply Or.inl; admit
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| upper d => apply Or.inr
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| diag => apply Or.inl; apply Nat.le_refl
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/--
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error: Invalid alternative name `lower2`: Expected `lower`
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---
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error: Alternative `lower` has not been provided
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-/
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#guard_msgs in
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theorem oneMissingAlt (p: Nat) : p ≤ q ∨ p > q := by
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cases p, q using elimEx with
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| upper d => apply Or.inl; admit
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| diag => apply Or.inl; apply Nat.le_refl
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| lower2 /- error -/ => apply Or.inr
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/--
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error: Duplicate alternative name `upper`
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---
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error: Alternative `lower` has not been provided
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-/
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#guard_msgs in
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theorem doubleAlt (p: Nat) : p ≤ q ∨ p > q := by
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cases p, q using elimEx with
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| upper d => apply Or.inl; admit
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| upper d /- error -/ => apply Or.inr
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| diag => apply Or.inl; apply Nat.le_refl
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/--
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error: Invalid occurrence of the wildcard alternative `| _ => ...`: It must be the last alternative
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-/
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#guard_msgs in
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theorem invalidWildCard (p: Nat) : p ≤ q ∨ p > q := by
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cases p, q using elimEx with
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| upper d => apply Or.inl; admit
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| _ /- error -/ => apply Or.inr
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| diag => apply Or.inl; apply Nat.le_refl
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/--
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error: Invalid alternative name `lower2`: There are no unhandled alternatives
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---
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error: unsolved goals
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case lower
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p delta✝ : Nat
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⊢ p > p + delta✝.succ
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-/
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#guard_msgs in
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theorem noAlt (p: Nat) : p ≤ q ∨ p > q := by
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cases p, q using elimEx with
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| upper d => apply Or.inl; admit
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| lower => apply Or.inr
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| diag => apply Or.inl; apply Nat.le_refl
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| lower2 /- error -/ => apply Or.inr
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